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Introduction to the Caesar Shift Cipher
Creating a Caesar Wheel
Using a Vigenere Square
Using Frequency Analysis
Encipher/Deciper Tool
Codes and Ciphers
Enrichment
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encountering problems with this site. About the Caesar Cipher

A Caesar shift substitution cipher is a simple cipher where every letter of the alphabet is substituted by another.

To start with, each letter of the alphabet is replaced by a number.

A 0
B 1
C 2
Z 25

Then we apply a shift, say 3, to the entire list by adding 3 to each number in turn. So,

A 0 + 3 = 3
B 1 + 3 = 4
C 2 + 3 = 5
Z 25 + 3 = 28

Finally the number is replaced with the letter that corresponds to the letter from the initial list.

i.e.A→ 0→ 3→ DB→ 1→ 4→ EC→ 2→ 5→ F... etc.

You will notice that with the letters X, Y and Z we have a problem here because no letters are assigned to 26, 27 and 28. This problem is resolved by using modular arithmetic, in this case we are using mod 26 [more].

So,X→ 23→ 26→ 0→ AY→ 24→ 27→ 1→ BandZ→ 25→ 28→ 2→ C.

The following table shows the complete alphabet after a Caesar shift of three places. Click on the buttons below to modify the table for any shift.

Caesar Shift Table

Shift size:

Further Information

Creating a Caesar shift cipher

  • The Caesar shift wheel. [more]

Deciphering a Caesar shift cipher

  • Using the Vigenere square. [more]
  • Using frequency analysis. [more]

Caesar shift cipher encipher/decipher tool. [more]

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